Numerous creations involving fast operating piston clocks have seem to randomly drop the redstone wiring that composes them. This effects repeaters, wires, and torches. It does not seem to effect comparators or redstone blocks. It is random, and does not occur based on chunk, but rather seems to occur among only wires that are linked together. I have not witnessed the wires dropping, and it seems only to occur when they are not in view.